Invalid output when using global assignments

[AshleyScirra]

Uglify version (uglifyjs -V) 3.19.2

JavaScript input

globalThis.Unused = {};

globalThis.Namespace = {};
globalThis.Namespace.Foo = {
    bar: false,
};

The uglifyjs CLI command executed or minify() options used.

uglifyjs input.js --compress --beautify --output output.js

JavaScript output or error produced.

globalThis.Unused = {}, globalThis.Namespace.Foo = {
    bar: !(globalThis.Namespace = {})
};

Note in the output code there is an error as self.Namespace is not declared. For some reason the creation of Namespace has been moved to after it is used, so UglifyJS has transformed this from working code in to broken code.

If you comment out the line globalThis.Unused = {}; then it works correctly - so it looks like UglifyJS encountering the first global ends up in a state which then causes it to process the second global incorrectly.

[AshleyScirra]

The problem appears to be with the collapse_vars option. It can be worked around by passing false for that option, e.g.:

uglifyjs input.js --compress collapse_vars=false --beautify --output output.js

produces the following working output:

globalThis.Unused = {}, globalThis.Namespace = {}, globalThis.Namespace.Foo = {
    bar: !1
};

[alexlamsl]

Thanks for the detailed report − investigating.

[alexlamsl]

Patch released in uglify-js@3.19.3

[AshleyScirra]

Thanks!